Complex Coding Tasks: Recursion and More

You're a software engineer at RTX working on ground-side telemetry decoding for a sensor payload. Frames arrive over a serial link as raw bytes; a small C module validates each frame, decodes a big-endian sensor reading, accumulates a checksum recursively, and tracks the largest reading seen so far. In bench testing the decoder either hangs, crashes, or reports readings that don't match what the test rig actually sent.

#include <stdint.h>

#define FRAME_SIZE 8
#define IS_VALID_FRAME(f) f[0] == 0xAA && f[1] == 0x55

int32_t bytes_to_int32_be(uint8_t *bytes) {
    return (bytes[0] << 24) | (bytes[1] << 16) | (bytes[2] << 8) | bytes[3];
}

int checksum_recursive(uint8_t *frame, int index) {
    if (index == FRAME_SIZE) {
        return 0;
    }
    return frame[index] + checksum_recursive(frame, index);
}

int32_t find_max_reading(int32_t *readings, int count) {
    int32_t max = 0;
    for (int i = 0; i < count; i++) {
        if (readings[i] > max) {
            max = readings[i];
        }
    }
    return max;
}

void process_telemetry_frame(uint8_t *frame, int32_t *readings_out, int *count_out) {
    if (IS_VALID_FRAME(frame) == 0) {
        return;
    }

    int32_t reading = bytes_to_int32_be(&frame[2]);
    readings_out[*count_out] = reading;
    *count_out = *count_out + 1;
}

Find every bug in this program: there's a macro-expansion bug, a recursion bug, an endianness/casting bug, and a couple of logic bugs around the max-value and buffer tracking. Walk through each one, exactly how it manifests, and how you'd fix it.

Use audit_decoder(source_code) and return the findings in source order as a list of objects containing bug, manifestation, and fix. The supplied source text is the decoder shown above.